Off The Grid

Now that we have water out of the well, we need to send it to the house! But we don't want the pump to turn on every time we turn on a faucet do we? That would wear out the pump. What we want is for the pump to build up pressure in a storage tank and turn on every few hours as needed. Since water does not compress, we need some sort of tank with air on top and water in the bottom. If we just put water into a tank and allow it to touch the air in the tank, the water will absorb the air and eventually the tank won't have air in it. So we often use a rubber bladder to hold the water.

Here is a system diagram

The original versions of this system didn't use bladders but they did have a way to make sure that enough air stayed in the tank! Remember a few days ago we talked about freeze proofing with a weep hole? When the pump shuts off, the well leaks down a little and we get air into the piping. When the pump runs again, that air gets pushed into the tank along with the water from well. There is a valve inside the tank about half way up called "air volume control valve" that makes sure the tank stays half full of air and lets out any excess air.

For the past two days we have talked about hand pumps. Today we'll talk about electric pumps. Electric pumps are called "shallow well", "jet pumps" and "submersible" pumps. If the water table is not lower than 15ft, you can use a shallow well pump to suck water out of the well. A jet pump cheats this a little by pumping water down the well case in a 2nd pipe, doing a u-turn at the bottom and using the momentum of water to suck additional water out of the well. This is not very efficient!

There are two different types of hand pumps... deep and shallow. Shallow well pumps suck water from the well. They can only suck water that is up to 15ft deep or so. If the water is deeper than that, you can't suck hard enough to lift it. So all the working parts are in the top of the well. Most of us are familiar with an old "pitcher pump".

If your water level is lower than 15-20ft, you have to use a deep well pump. These pumps put the check valves down at the bottom of the well and water is pushed upward. There is usually a rod that runs down inside the water pipe that is used to push and pull that pump cylinder at the bottom of the well. Note that you can push water any distance but you can only suck water 15 ft vertical. Also, look for the weep hole in this diagram above. Remember yesterday we talked about freezing? Now you know why there is a weep hole!

Modern hand pumps like Simple Pump or Bison tell us to drill a small 1/8" 3mm hole in the water riser pipe that will allow water to slowly drain back into the well a few feet deep. This works because on these pumps, the working cylinder is all the way at the bottom of the well pushing water up from the bottom. Yes a tiny amount of water leaks out when you pump but it is worth it because it prevents freezing.

Do you know that when water freezes, the ice expands? This can cause metal to crack and that's bad if that metal is your water pump! Old pitcher pumps have a feature where when you are done pumping water, if you pull up all the way on the handle they will open all the check valves and allow the water to drain back into the well. Now it won't crack when it gets below freezing!

As promised here's the series about pumps that was on the kids channel.

Decided we haven't had rain in a while, it might be interesting to see what a difference dusty vs clean panels makes. not a lot. You can see the red line is the estimated production increasing as the sun rises in the sky... you can see the lost production where I was washing them and the rise in production where the water had cooled them down a little. Net result, the light haze of dust isn't making any difference.

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